The present invention relates to a scanner and more particularly to a scanner of the type included in an electrophotographic copier, laser printer, facsimile apparatus or similar image forming apparatus for steering a light beam with a polygonal mirror.
A conventional scanner of the type described includes a polygonal mirror mounted on a flange and a scanner motor for causing the mirror to rotate. The polygonal mirror in rotation reflects a light beam representative of image information. The problem with this conventional scanner is that it is bulky because the polygonal mirror and scanner motor are physically separate from each other and because the scanner motor cannot be sufficiently reduced in size. The scanner therefore occupies a substantial space when mounted on a laser printer or similar image forming apparatus, obstructing the miniaturization of the entire apparatus.
Japanese, Patent Laid-Open Publication No. 8-62527, for example, teaches a scanner motor constructed to reduce the size of the polygonal mirror. The scanner motor disclosed in this document includes a rotor yoke having hexagonal sides. Chip mirrors each are adhered to one of the hexagonal sides of the rotor yoke, forming a polygonal mirror. The chip mirrors, however, not only increase the number of parts of the scanner, but also need highly accurate adhesion to the rotor yoke. In addition, the chip mirrors are apt to come off or deform after adhesion due to a centrifugal force.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Publication No. 6-40177 and Japanese Patent Laid-Open Publication No. 9-230269.